1. Field of the Invention
The present invention generally relates to a magnetic head which is mounted on a magnetic recording, reproducing apparatus for recording/reproducing the information stored on a magnetic recording medium. More particularly, the present invention relates to a magneto-resistive head.
2. Description of the Prior art
A conventional magneto-resistive head shown in FIG. 4 has been disclosed in Japanese Laid-Open Patent Publication No. 50-134624. A gap insulating layer 52, a rectangular magneto-resistive element 53 of a Ni-Fe alloy thin film or the like, a pair of electrodes 54a, 54b, inclined electrodes 57a, 57b, 57c, 57d, 57e, a front yoke 56 and a back yoke 58 and so on for guiding magnetic signal flux stored on the magnetic recording medium from the magnetic tape sliding face 55 to the magneto-resistive element are sequentially laminated on a magnetic base plate 51 through an insulating layer (not shown). The magneto-resistive head is connected to an exterior circuit through terminals 59a, 59b. The magneto-resistive element must be of a single magnetic domain and have a specific direction of magnetization in order to operate normally in the conventional magneto-resistive head. FIG. 5 shows an essential portion of the magneto-resistive element. When the driving current flows in the direction of reference numeral 62, the initial magnetization of the magneto-resistive element must be in the direction shown by reference numeral 61.
The reasons for this will be described hereinafter. If the magneto-resistive element were magnetized in mutually opposite directions as shown by reference numerals 61, 66 in FIG. 5, the change in resistance in each portion of the element would become reverse in terms of polarity when the signal magnetic field 64 flows into the magneto-resistive element. This effect extremely reduces the output. Because the reverse direction of magnetization exists within the magneto-resistive element, Barkhausen noise can be generated.
In the conventional type of magneto-resistive head, therefore, the magnetizing direction within the magneto-resistive element should be in direction 61.
However, in the conventional magneto-resistive head, the magnetizing direction changes in a disturbance magnetic field of approximately 1600A/m. The reproducing output thus becomes unstable and includes noise.